Abstract—Laser engraving is a manufacturing method for those

applications where previously Electrical Discharge Machining

(EDM) was the only choice. Laser engraving technology removes

material layer-by-layer and the thickness of layers is usually in the

range of few microns. The aim of the present work is to investigate

the influence of the process parameters on the surface quality when

machined by laser engraving. The examined parameters were: the

pulse frequency, the beam speed and the layer thickness. The surface

quality was determined by the surface roughness for every set of

parameters. Experimental results on Al7075 material showed that the

surface roughness strictly depends on the process parameters used.

Keywords—Laser engraving, Al7075, Yb:YAG Laser, Laser

process parameters, Material Roughness

I. INTRODUCTION

ASER engraving is one of the most promising

technologies to be used in rapid prototyping in order to

engrave or mark an object. In this method, a laser beam is used

to ablate a solid bulk, following predetermined patterns. The

desired pattern is created by repeating this process on each

successive thin layer. There are many advantages of this

method compared to traditional machining, such as: no

mechanical contact with the surface, reduction in industrial

effluents, a fine accuracy of machining and an excellent quality

and detail on the final product [1], [2]. The laser engraving

method has many applications in industry, such as: creation of

molds and dies, engraving information i.e. names and serial

numbers in the silicon chips, direct engraving of the expiry

date on food package, engraving of an image beneath the

surface of a solid material (usually glass), direct engraving of

flexographic plates and cylinders.

The main research areas on the laser engraving are the

process parameters and the resulted surface roughness. Genna

F.Agalianos is with the Technical University of Crete, University Campus,

Kounoupidiana, Chania GR73100, Greece (e-mail:

fotisagalianos@gmail.com).

S.Patelis is with the Technical University of Crete, University Campus,

Kounoupidiana, Chania GR73100, Greece (e-mails: spatelis@hotmail.com).

P. Kyratsis is with the Technological Educational Institution of West

Macedonia, Kila Kozani, GR50100, Greece (e-mail: pkyratsis@teikoz.gr).

E. Maravelakis is with the Technological Educational Institution of Crete,

Chania GR73100, Greece (e-mail: marvel@chania.teicrete.gr).

E.Vasarmidis is with Iconotechniki S.A., Athens, Greece (e-mail:

info@iconotechniki.gr).

A. Antoniadis is with the Technical University of Crete, University

Campus, Kounoupidiana, Chania GR73100, Greece (corresponding author e-

mail: antoniadis@dpem.tuc.gr).

et al. aimed in studying the process parameters affecting the

material removal rate and surface roughness on C45 steel [2].

A research which was developed by Qi et al. aimed to find the

relationship between the frequency of the laser and the quality

characteristics on stainless steel [3]. Another research

developed by Leone et al. had as its purpose to investigate how

the process parameters are affecting the material removal rate

in different types of wood [4]. The research which was

conducted by Leone et al. had as its purpose to determine the

correlation between process parameters and their visual

outcome [5].

II. EXPERIMENTS

A. Equipment

The engraving tests were performed by using a Q-Switched

100 W Yb:YAG laser, with fundamental length λ = 1064 nm.

The beam is moved through two galvanometer mirrors onto

the workpiece and the final focused beam diameter is about 50

µm. The range of the frequency that can be used by the laser is

between 4–50 kHz, the corresponding range in speed is

between 50-1000 mm/s and the removal material thickness per

layer can be between 1-15µm depending on the material. The

laser system is controlled via a PC, which allows the

generation of the geometric patterns and the setting of the

process parameters: the beam power, the pulse frequency (f),

the scan speed (v) and the removal material thickness per layer

(Figure 1).

B. Process Parameters

In order to perform the engraving tests an Al7075 plate was

used. Cycle areas of 12 mm diameter and 200 µm depth were

obtained on the samples by engraving circles with the same

dimensions and different parameters (Figure 2). The pulse

frequency was fixed at 20, 30, 40, 50 kHz, the scan speed was

varied in the range 200-1000 mm/s and the layer thickness was

fixed at 2, 4, 6, 8 µm (Figure 3). The surfaces of the engraved

cavities were measured by a Surface Roughness

Measurement Diavite Compact. Five measurements were

performed in the same direction for each circle and the average

value was calculated.

C. Results and Discussion

The influence of the process parameters on the laser

engraving are depicted in the following two figures. Figure 4

presents four diagrams showing the surface roughness as a

F.Agalianos, S.Patelis , P. Kyratsis, E. Maravelakis, E.Vasarmidis, A.Antoniadis

Industrial Applications of Laser Engraving:

Influence of the Process Parameters on

Machined Surface Quality

L

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Fig. 1 The Q-Switched 100 W Yb:YAG laser

Fig. 2 The engraving tests on Al7075 plate

function of scan speed for different frequencies, for layer

thickness 2, 4, 6 and 8 µm.

It’s obvious from all the cases of figure 4, that surface

roughness has in general its smallest values for a frequency of

20 kHz. More specifically in the diagram with a layer

thickness of 2 µm and for a frequency equal to 30 kHz, the

surface roughness decreases continuously with the increase of

the scan speed. When the frequency is 20 kHz the surface

roughness increases for all increased values of the scan speed

and when a frequency of 40 kHz is used, the surface roughness

fluctuates throughout the range of all scan speed values.

In the diagram with a layer thickness of 4 µm, when a

frequency of 30 kHz is used, the resulted surface roughness

decreases until the scan speed reaches 500 mm/s and then

increases with the scan speed. In the case of using a frequency

of 20 kHz the roughness slightly increases with the increase of

scan speed and for a frequency of 40 kHz it slightly decreases

for the same conditions. A similar behavior is depicted in the

diagram for the layer thickness of 6 µm, with the difference

that for a frequency of 20 kHz the surface roughness decreases

with the increase of the scan speed. As expected in the diagram

for the layer thickness of 8 µm, there are not impressive

differences in the resulted roughness trends, except in the case

of 20 kHz where surface roughness is almost constant.

Figure 5 presents three diagrams showing the surface

roughness as a function of the layer thickness for different scan

speeds (starting from 400 up to 1000mm/s) and for frequencies

of 20, 30 and 40 kHz respectively. The three scan speeds used

for each diagram were selected because they have resulted the

smallest values of surface roughness.

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Fig. 3 The experimental parameters used

Fig. 4 Surface roughness as a function of scan speed for different frequencies (20-30-40 kHz)

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Fig. 5 Surface roughness as a function of layer thickness for different scan speed values

For the frequencies of 20 and 40 kHz the surface

roughness: a)decreases when the layer thickness receives a

value of 2 or 4 µm, b)remains almost stable for a layer

thickness of 6 µm and c)increases for a layer thickness of 8

µm. It worth mentioning that the resulted surface roughness

converges to the same value as the layer thickness increases,

when the three scan speeds are used.

For the frequency of 30 kHz and scan speeds of 400

mm/s and 600 mm/s, the surface roughness a)decreases for

layer thickness of 2 µm to 4µm, b)is almost stable for layer

thickness of 4 µm and 6 µm and c)increases for a layer

thickness of 8 µm. In the case that the scan speed is 500

mm/s the surface roughness decreases for layer thickness 4

µm and then increases until the layer thickness reaches 8

µm.

III. CONCLUSIONS

Based on the experimental work of the present paper in

laser engraving of Al7075 using a Q-switched Yb:YAG

fibre laser, it can be summarized that the surface roughness

strongly depends on the frequency and the scan speed used.

In addition it was proven that the resulted roughness

depends less by the layer thickness. When considering all

the experimental data of the current experimental plan, the

best surface roughness was achieved when using a

frequency of 20kHz, a scan speed in the range of 600-

700mm/s and a layer thickness of 4 and 6µm.

ACKNOWLEDGMENT

The authors wish to thank the General Secretariat for

Research and Technology of Ministry of Education,

Lifelong Learning and Religious Affairs in Greece for their

financial support (via program Cooperation: Partnership of

Production and Research Institutions in Small and Medium

Scale Projects, Project Title: “Using of Micromachining

Reverse Engineering Actions and Digitization for the

Development of New Products and Copies of Cultural

Heritage”).

REFERENCES

[1] B. N. Dahotre and S.P. Harimkar, Laser Fabrication and Machining

of Materials. Springer, 2008.

[2] S. Genna, C. Leone, V. Lopresto, L.Santo, and F. Trovalusci, “Study

of fibre laser machining on C45 steel: influences of process

parameters on material removal rate and roughness”, Int. J Mater

Form, Vol 3, pp.1115-1118, 2010.

[3] J. Qi, K.L.Wang and Y.N. Zhu, “A study on the Laser marking

process of stainless steel”, Journal of Materials Technology, Vol.

139, pp. 273-276, 2003.

[4] C. Leone, V. Lopresto and I. De Iorio, “Wood engraving by Q-

switched diode-pumped frequency-doubled Nd:YAG green Laser”,

Optics and Laser in Engineering, Vol. 47, pp. 161-168, 2009.

[5] C. Leone, S. Genna, G. Caprino and I. De Iorio, “AISI 304 stainless

steel marking by a Q-switched diode pumped Nd:YAG Laser”,

Journal of Materials Processing Technology, Vol. 210, pp. 1297-

1303, 2010.

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